The invention relates to a flow regulator having a regulator housing in which, in a flow channel, an annular flow restrictor made of elastic material is provided that is pushed onto a fastening post and encompasses this post. The post has at least two fastening webs, oriented opposite the direction of pushing, whose free ends engage the flow restrictor from behind in a securing manner. The flow restrictor limits, between itself and at least one fixed part of the housing, a control gap whose flow cross-section can be modified by the flow restrictor, which deforms under the pressure difference that arises during flow.
A flow regulator of the type mentioned above is known in which the annular flow restrictor encompasses a central fastening post, past whose free end four fastening webs protrude. After the flow restrictor has been pushed onto the fastening post, through cold forming of the plastic material the fastening webs of the known flow regulator are bent outward and spread in such a way that they secure the annular flow restrictor against loss. However, the manufacturing method used has the disadvantage that, due to the plastic deformation of the originally sleeve-shaped fastening post, and due to the spreading of the fastening webs, an additional assembly step is required that slows the manufacturing process, the formed state is difficult to reproduce precisely, cracks can form in the material, and an apparently xe2x80x9cimperfectxe2x80x9d outward appearance of the flow regulator often results, leading to complaints from the purchasers of this flow regulator. In addition, if a crack results in the loss of a fastening web and there is a loss of counterpressure, the annular flow restrictor can fall out, resulting in corresponding disturbances in function.
In order to avoid such a cold forming of the fastening webs, a flow regulator is also known that has a fastening post having a massive construction. Securing projections that extend radially outward are provided at opposite sides on this massive fastening post. However, in order to manufacture this known flow regulator, an injection molding die is required that is fashioned as a split mold, or that has what are referred to as plungers in the area of the massive fastening post, so that the securing projections provided on the fastening webs are not sheared off when the injection-molded part is removed from the injection molding die. During the injection molding, the plungers are molded into the cavity from below. However, such plungers are sensitive components that are extremely susceptible to wear. Moreover, only a limited number of plungers can be used, because otherwise the underside of the housing is structurally weakened too much.
Therefore, a flow regulator has also been created whose central regulator core is constructed as a separate cross pin. This cross pin can be guided through the annular opening of the elastic flow restrictor and can subsequently be captively fixed in the regulator housing. However, it is disadvantageous that this known flow regulator is made up of a plurality of parts, and that a plurality of steps are also required in the manufacturing of the regulator housing.
The object of the present invention is therefore to create a functionally reliable flow regulator of the type indicated at the beginning that can be manufactured economically, with a low cost.
In a flow regulator of the aforementioned type, this object is achieved according to the present invention in that, in particular, the fastening webs are fashioned as resilient webs that can be flexibly inwardly deflected.
The flow regulator according to the invention has a fastening post at which the fastening webs that engage the flow restrictor from behind in a securing manner are fashioned as resilient webs that can be flexibly deflected inward. Through the flexible deflecting inward of the resilient webs, the outer spacing of their ends can be temporarily reduced far enough to allow the elastic flow restrictor to be pushed easily onto the fastening post. After the subsequent resilient expansion of the fastening webs, the flow restrictor is held on the fastening post in a practically captive fashion, so that a loss of the flow restrictorxe2x80x94for example, during shipping of the flow regulatorxe2x80x94is prevented, and functional disturbances are avoided. Because the fastening webs can be deflected, a flow regulator constructed as a plastic injection-molded part can also be easily removed from a simple injection molding die, without requiring expensive split molds or injection molding dies having plungers, which are expensive and liable to malfunction.
It is particularly advantageous if the fastening webs engage the flow restrictor from behind with a holding cam or similar expansion that expands the web cross-section, situated on the free end of each web. This expansion, which expands the web cross-section outward in the radial direction, forms an undercut that holds the flow restrictor securely on the fastening post.
In order to facilitate a simple installation of the flow restrictor on the fastening web, and to promote its secure support there, it is useful if the fastening post bears two to eight, and most preferably four fastening webs, arranged crosswise.
Here, a specific embodiment is preferred in which the fastening webs are distributed at uniform intervals around the perimeter of the post.
The fastening webs are integrally formed on the fastening post in particularly stable fashion if the fastening webs are separated from one another by longitudinal slots in the wall of the fastening post.
When the annular flow restrictor is slipped on, the flexible fastening webs are deflected inward practically automatically if the expansions provided on the fastening webs form a leading incline that expands radially outward in the direction of pushing. These installation or leading inclines on the ends of the fastening webs ensure that application can take place rapidly during the installation of the annular flow restrictor, and that the flow restrictor and fastening post find one another easily.
In order to avoid an undesired rotation or twisting of the flow restrictor while it is being pushed onto the fastening post, it is useful if the leading inclines form an angle of 201 to 301 in relation to the longitudinal axis of the web, depending upont the plastic material used.
It is particularly advantageous if the expansions are fashioned so as to be approximately wedge-shaped in longitudinal section.
A preferred specific embodiment according to the present invention provides that the peripheral wall of the housing is connected with the fastening post via radial connecting webs, and that the connecting webs limit the control gap between them.